Functional properties and sensory profile of coffee prepared by different brewing methods

Coffee is one of the main sources of antioxidants in the diet of many countries. The purpose of this research was to assess the effect of different brewing methods, particle size, and coffee quality on the total phenolic content, antioxidant capacity (AC), and sensory profile of the beverage. The brewing methods yielded differences in taste with higher bitterness in immersion methods. However, the main factors that influenced coffee extraction and taste were particle size and coffee type. A finer particle size allowed for greater phenolic and caffeine (CA) extraction (2.82 mg GA/mL; 1.01 mg CA/mL), resulting in higher bitterness and astringency. Additionally, the type of coffee resulted in a higher CA content in commercial coffee (Specialty: 0.72 ± 0.10 mg CA/mL; Commercial: 1.13 ± 0.14 mg CA/mL). The results showed that using a ratio of 1:20 and 1:15 for commercial and specialty coffee, respectively, yielded differences in AC using the DPPH method (Specialty: 11.54 ± 1.12 µmol/mL; Commercial: 10.20 ± 1.88 µmol/mL) but not with the ABTS method (Specialty: 10.38 ± 1.23 µmol/mL; Commercial: 10.37 ± 1.13 µmol/mL). Similarly to the ABTS method, no differences in the total phenol content of the coffee cup were observed (Specialty: 2.52 ± 0.40 mg/mL; Commercial: 2.43 ± 0.28 mg/mL). Thus, the findings suggest that specialty coffee offers consumers a more balanced cup with less CA content. This allows for more coffee consumption without an excessive intake of CA. However, consumers can adjust the functionality, sensory profile, and CA content of a coffee cup by modifying the particle size and the brewing method used.

Optimization of the antioxidant capacity of mangosteen peels (Garcinia mangostana L.) extracts: Management of the drying extraction processes

Mangosteen peel is a source of natural phenolic antioxidants. During processing, the quality and quantity of these compounds in the final product are altered. Sometimes, the important causal relationships are not easy to establish and thus process management is difficult. This is especially true when biochemical changes can occur as in the case of the drying and extraction process of bioactive materials. The aim of this work was to formulate and solve an optimization problem in order to obtain the appropriate values of the operating conditions that maximize the antioxidant capacity of the dried mangosteen peel extracts. The drying process was analyzed under different drying air temperatures (T) (50℃, 60℃, 70℃ and 80℃) at air velocity of 1 ms^-1. The extraction process was done under conventional and ultrasound-assisted extraction at 400 W. Antioxidant capacity was measured by 1,1-diphenyl-2-picrylhydrazyl assay. To solve the optimization problem formulated, an artificial neural network was developed. The resolution of the optimization problem allowed the establishment of the optimal operating conditions of the process, maximizing the antioxidant capacity values depending on the characteristics of the process. Results showed that the best operating conditions to maximize the antioxidant capacity of mangosteen peels were a drying temperature of 70℃ and using high-power ultrasound as extraction method.